Technical Abstract:
One important criterion of polymeric material selection and packaging design for fresh produce is choosing the material with suitable ratio of carbon dioxide and oxygen permabilities (PCO2/P O2), to the respiratory proportion of the targeted produce. The ratio of [O2] and [CO2] in the head space varies depending on the polymeric material, influence the respiration and deterioration rates of fresh produce. The material with low ratio value will prevent the majority of CO2 from permeating through the package. Once a packaging material is selected for a particular commodity, it is crucial that its PCO2/PO2 ratio be maintained through the shelf-life of the product, as in the case of modified atmosphere packaging (MAP) where the stable gaseous ratio in the package headspace is necessary. Several factors can affect the PCO2/PO2 of the packaging system, such as temperature fluctuation during storage and transportation, as well as the exposure of the packaging material to reactive chemical compounds treatment that may affect the integrity of the packaging material.
In this study, the effects of ClO2 gas, a strong oxidizing agent, which has potential to be utilized as an antimicrobial agent in food packaging system, is being considered. It has been observed that several polymeric materials are being affected by ClO2 as a consequence the PCO2 and PO2 is also being affected. Therefore the PCO2 and PO2 (cc.m.m-2.s-1.Pa-1) of ten polymeric materials, i.e. LDPE, HDPE, LLDPE, PP, PS, PET, PLA, PVC, nylon and multilayer of EVA/EVOH/EVA, are treated with gaseous ClO2 for 1, 7 and 14 days, and their PCO2 and PO2 values determined. The polymeric profile such as the FT-IR spectrum of each polymer material before and after the exposure will be presented and correlated with the permeability data. Some initial results indicated that the PCO2/PO2 ratio of PET decrease from 5.0 to 4.2 after 14 days of exposure to low levels of ClO2 gas, while for LDPE, the ratio increase from 6.0 to 6.5, and from 4.8 to 5.6, for PS sample after few hours of exposure to ClO2